1. Field of the Invention
The present invention relates to a current detector for detecting a current flowing through an electric circuit mounted to equipment such as an automobile, and more particularly, to a technique for enhancing a detection precision of a current when a plurality of conductors are arranged side-by-side.
2. Description of Related Art
There is a conventionally known current detector for detecting a current flowing through an electric circuit mounted in, e.g., an automobile using a Hall element which is one of magnetic-electric power converting element. One example of such current detectors is disclosed in Japanese Patent Application Laid-open No. H5-223849. This current detector comprises a conductor flowing a current to be detected (which will be referred to as xe2x80x9cto-be detected currentxe2x80x9d, hereinafter), and having a notch formed on the same plane, or having a loop-like current path formed by bending. The current detector also comprises a magnetic-electric power converting element for converting a magnetic flux generated by the to-be detected current I flowing to the conductor.
In this current detector, if the to-be detected current flows to the loop-like current path formed on the conductor, a magnetic flux is generated. This magnetic flux is converted into an electric signal by the magnetic-electric power converting element and, with this conversion, the electric signal is proportional to a magnitude of the to-be detected current. Since this current detector can sense more than two times magnetic fluxes as compared with a case in which the magnetic-electric power converting element is disposed in the vicinity of a linear conductor, it is possible to enhance the detecting precision of a current. Since his current detector can sense more than two times magnetic fluxes as compared with a case in which the magnetic-electric power converting element is disposed in the vicinity of a linear conductor, it is possible to enhance the detecting precision of a current.
Japanese Patent Application Laid-open No. S63-253264 (Japanese Patent Publication No. H8-3499) discloses another example of the current detector. This current detector comprises a conductor wire through which a to-be detected current flows, magnetic-electric power converting elements for converting a magnetic field generated around the conductor wire when the to-be detected current flows through the conductor wire in opposed regions around the conductor wire, and a synthesizing section for synthesizing magnetic-electric power conversion outputs from the magnetic-electric power converting elements.
According to this current detector, the magnetic-electric power converting elements have the same characteristics, and they receive the same magnetic fields in the opposite direction from each other with respect to the magnetic field generated when a current flows through the conductor wire. Therefore, since the outputs from the elements have opposite phases, the output of the synthesizing section about twice as large as the output of one of the elements when these outputs are differentially synthesized by the synthesizing section. On the other hand, when the entire current detector is affected by an external magnetic field, the outputs of the magnetic-electric power converting elements are the same phases with respect to the external magnetic field. Therefore, in the outputs differentially synthesized by the synthesizing section, an output signal based on the external magnetic field is canceled.
However, in the case of the current detector disclosed in Japanese Patent Application Laid-open No. H5-223849, the magnetic flux generated by a current flowing through a conductor other than the to-be measured conductor becomes disturbance which affects the detection result and thus, there is a problem that a current flowing through the to-be measured conductor can not be detected precisely. Especially when a current is detected using a magnetic-electric power converting element in an environment in which a plurality of conductors are arranged side-by-side such as an electric connection box of an automobile, since the magnetic flux generated by a current flowing through a conductor other than the to-be measured conductor interferes the detecting operation, there is a problem that the current detecting precision can not be enhanced.
Further, in the case of the current detector disclosed in Japanese Patent Application Laid-open No. S63-253264 (Japanese Patent Publication No. H8-3499), it is necessary to use two magnetic-electric power converting elements with respect to one conductor, there is a problem that the costs of the current detector is increased.
It is an object of the present invention to provide an inexpensive current detector capable of precisely detecting a current flowing through a to-be measured conductor even when a plurality of conductors are arranged side-by-side such as an electric connection box of an automobile.
To achieve the above object, according to a first aspect of the invention, there is provided a current detector comprising a linear conductor, a linear to-be measured conductor disposed substantially in parallel to the conductor and through which a to-be measured current flows, a magnetic-electric power converting element disposed in the vicinity of the to-be measured conductor such that a magnetic flux generated by the to-be measured current flowing through the to-be measured conductor enter into a magnetic-force sensing face substantially perpendicularly, and a substrate for supporting the conductor and the to-be measured conductor such that the magnetic flux generated by a current flowing through the conductor becomes substantially parallel to the magnetic-force sensing face in the magnetic-force sensing face of the magnetic-electric power converting element.
With the first aspect, a positional relation between the magnetic-electric power converting element disposed in the vicinity of the to-be measured conductor and a conductor other than the to-be measured conductor is adjusted by the supporting substrate supporting these members. That is, the to-be measured conductors are disposed on the substrate such that the magnetic flux generated by the to-be measured current flowing through the to-be measured conductor enters into the magnetic-force sensing face perpendicularly, and the magnetic flux generated by a current flowing through the conductor other than the to-be measured conductor becomes substantially parallel to the magnetic-force sensing face in the magnetic-force sensing face of the magnetic-electric power converting element. Therefore, the magnetic-electric power converting element only senses a magnetic flux generated by the to-be measured current flowing through the to-be measured conductor, and does not sense a magnetic flux generated by a conductor other than the to-be measured conductor. Thus, it is possible to precisely detect a to-be measured current flowing through the to-be measured conductor. Further, since the current detector has one magnetic-electric power converting element, it is possible to provide an inexpensive current detector.
According to a second aspect of the invention, there is provided a current detector comprising a to-be measured conductor formed with a bent portion which is bent into a U-shape or a crank-shape and through which a to-be measured current flows, a magnetic-electric power converting element disposed in the vicinity of the bent portion such that a magnetic flux generated by the to-be measured current flowing through the to-be measured conductor enter into a magnetic-force sensing face substantially perpendicularly, and a linear conductor disposed such that a magnetic flux generated when a current flows becomes substantially parallel to the magnetic-force sensing face in the magnetic-force sensing face of the magnetic-electric power converting element.
With the second aspect, a positional relation between the magnetic-electric power converting element disposed in the vicinity of the to-be measured conductor and a conductor other than the to-be measured conductor is adjusted by the bent portion formed on the to-be measured conductor. That is, the to-be measured conductor is formed with the bent portion, and the magnetic-electric power converting element is disposed in the bent portion such that the magnetic flux generated by the to-be measured current flowing through the to-be measured conductor enters into the magnetic-force sensing face of the magnetic-electric power converting element perpendicularly. The conductor other than the to-be measured conductor is disposed such that the magnetic flux generated flowing through the conductor becomes substantially parallel to the magnetic-force sensing face in the magnetic-force sensing face of the magnetic-electric power converting element. Therefore, like the first aspect, the magnetic-electric power converting element only senses a magnetic flux generated by the to-be measured current flowing through the to-be measured conductor, and does not sense a magnetic flux generated by a conductor other than the to-be measured conductor. Thus, it is possible to precisely detect a to-be measured current flowing through the to-be measured conductor. Further, since the current detector has one magnetic-electric power converting element, it is possible to provide an inexpensive current detector.
According to a third aspect of the invention, in the current detector of the first aspect, the magnetic-electric power converting element is disposed such that a plane including the conductor passes through a substantially center of the magnetic-force sensing face of the magnetic-electric power converting element and crosses the magnetic-force sensing face substantially perpendicularly.
With the third aspect, the magnetic flux generated when a current flows through a conductor other than the to-be measured conductor becomes substantially parallel to the magnetic-force sensing face in the magnetic-force sensing face of the magnetic-electric power converting element. Therefore when a current flowing through the to-be measured conductor is to be detected, it is possible to substantially eliminate an influence of the magnetic flux generated by the conductor other than the to-be measured conductor.
According to a fourth aspect of the invention, there is provided a current detector comprising a plurality of to-be measured conductors through which to-be measured currents flow respectively, wherein each of the to-be measured conductors includes a bent portion bent into a U-shape or a crank-shape, magnetic-electric power converting elements are disposed in the vicinity of the bent portions of the to-be measured conductors, respectively, such that a magnetic flux generated by a to-be measured current flowing through each of the to-be measured conductors enters into the magnetic-force sensing face substantially perpendicularly, and the plurality of to-be measured conductors are disposed in parallel to one another and disposed such that the bent portions of the to-be measured conductors are not aligned with one another in a longitudinal direction of each the to-be measured conductor.
With the fourth aspect, the magnetic-electric power converting element is disposed in each of the bent portions of the plurality of to-be measured conductors disposed substantially parallel to one another, and the bent portions of the to-be measured conductors are disposed such that they are not aligned to one another in the longitudinal direction of the to-be measured conductor. Therefore, each to-be measured conductor does not influence the magnetic-electric power converting element disposed in other to-be measured conductor. Therefore, it is possible to precisely detect a current flowing through each of the plurality of to-be measured conductors with out being affected by other to-be measured conductors.
According to a fifth aspect of the invention, in the current detector of the fourth aspect, each one of said magnetic-electric power converting elements is disposed such that a plane including said to-be measured conductor of the other magnetic-electric power converting elements excluding said bent portions passes through a substantially center of said magnetic-force sensing face of said former one magnetic-electric power converting element and crosses said magnetic-force sensing face substantially vertically.
With the fifth aspect, in a magnetic-force sensing face of a magnetic-electric power converting element disposed in a certain to-be measured conductor, a magnetic flux generated when a current flows through another to-be measured conductor can precisely become parallel to this magnetic-force sensing face. Therefore, when a current flowing through each to-be measured conductor is to be detected, it is possible to substantially eliminate an influence of a magnetic flux generated by other to-be measured conductor.
According to a sixth aspect of the invention, there is provided a current detector comprising a linear to-be measured conductor through which a to-be measured current flows, a magnetic-electric power converting element disposed in the vicinity of the to-be measured conductor such that a magnetic flux generated by the to-be measured current flowing through the to-be measured conductor enter into a magnetic-force sensing face substantially perpendicularly, and a linear conductor having parallel branch paths for bisecting a flowing current by through holes, and disposed such that magnetic fluxes generated when currents flow through the branch paths cross each other at equal angles with respect to the magnetic-force sensing face on the magnetic-force sensing face of the magnetic-electric power converting element.
With the sixth aspect, magnetic fluxes generated when currents flow through the branch paths cross each other in the magnetic-force sensing face of the magnetic-electric power converting element at equal angles with respect to this magnetic-force sensing face. Therefore, vertical components with respect to the magnetic-force sensing faces of the magnetic fluxes are canceled by each other. Thus, when a current flowing through the to-be measured conductor is to be detected, it is possible to substantially eliminate an influence of the magnetic flux generated by the conductor other than the to-be measured conductor.
According to a seventh aspect of the invention, in the current detector of the sixth aspect, the magnetic-electric power converting element is disposed such that a plane separated away from each of the branch paths through equal distances passes through substantially center of the magnetic-force sensing face of same magnetic-electric power converting element and crosses the magnetic-force sensing face substantially perpendicularly.
With the seventh aspect, a magnetic flux generated when a current flows through a conductor other than the to-be measured conductor is precisely canceled in the magnetic-force sensing face of the magnetic-electric power converting element. Therefore, when a current flowing through the to-be measured conductor is to be detected, it is possible to substantially eliminate an influence of the magnetic flux generated by the conductor other than the to-be measured conductor.
According to an eighth aspect of the invention, in the current detector of the first aspect, the magnetic-electric power converting element is secured to the to-be measured conductor.
With the eighth aspect, since a position of the magnetic-electric power converting element with respect to the to-be measured conductor can be fixed precisely, it is possible to set a magnetic flux generated when a current flows through the to-be measured conductor such that the magnetic flux precisely enters into the magnetic-force sensing face of the magnetic-electric power converting element perpendicularly. Further, a position of the other conductor or the to-be measured conductor with respect to the magnetic-electric power converting element is precisely determined by positioning the other conductor or the to-be measured conductor with respect to the to-be measured conductor and thus, it is easy to assemble the current detector.
According to a ninth aspect of the invention, in the current detector of the second aspect, the magnetic-electric power converting element is disposed such that a plane including the conductor passes through a substantially center of the magnetic-force sensing face of the magnetic-electric power converting element and crosses the magnetic-force sensing face substantially perpendicularly.
With the ninth aspect, a magnetic flux generated when a current flows through a conductor other than the to-be measured conductor becomes substantially parallel to the magnetic-force sensing face. Therefore, when a current flowing through the to-be measured conductor is to be detected, it is possible to substantially eliminate an influence of the magnetic flux generated by the conductor other than the to-be measured conductor.